Investigations

An investigation is the dated record of a fault chased or a question measured: what was tried, what was measured, what was excluded. It is append-only while open. When it ends, set status: closed, state the outcome in its first paragraph, and link the decision record or commit that resolved it.

Investigations are kept rather than archived. They hold the evidence behind the rules in the design documents, and the mechanisms already excluded, so the next person chasing a similar fault starts from them.

Cross-cutting investigations live here as YYYY-MM-short-title.md. One that belongs to a single subsystem lives in that subsystem's design/investigations/.